/*
 ============================================================================
 Page	     : 510-512
 Name        : dualview.c
 Date	     : 20210407
 Author      : Hbue 18060333
 Copyright   : Your copyright notice
 Description : 位字段和按位运算符
 ============================================================================
 */

#include <stdio.h>
#include <stdbool.h>
#include <limits.h>

/* 位字段符号常量 */
/* 边框线样式 */
#define SOLID  0
#define DOTTED 1
#define DASHED 2

/* 三原色 */
#define BLUE	4
#define GREEN	2
#define RED	1

/* 混合色 */
#define BLACK 0
#define YELLOW  (RED | GREEN)
#define MAGENTA (RED | BLUE)
#define CYAN  (GREEN | BLUE)
#define WHITE (GREEN | BLUE | RED)

/* 按位方法中用到的符号常量 */
#define OPAQUE 			0x1
#define FILL_BLUE		0x8
#define FILL_GREEN		0x4
#define FILL_RED		0x2
#define FILL_MASK		0xE
#define BORDER			0x100
#define BORDER_BLUE 		0x800
#define BORDER_GREEN 		0x400
#define BORDER_RED 		0x200
#define BORDER_MASK		0xE00
#define B_SOLID			0
#define B_DOTTED		0x1000
#define B_DASHED		0x2000
#define STYLE_MASK		0x3000

const char *colors[8] = { "black", "red", "green", "yellow", "blue", "magenta", "cyan", "white" };

struct box_props
{
	bool opaque 				: 1;
	unsigned int fill_color 		: 3;
	unsigned int 				: 4;
	bool show_border 			: 1;
	unsigned int border_color 		: 3;
	unsigned int border_style 		: 2;
	unsigned int 				: 2;
};

union Views		/* 把数据看做结构或unsigned short类型的变量 */
{
	struct box_props st_view;
	unsigned short us_view;
};

void show_settings(const struct box_props *pb);
void show_settings1(unsigned short);
char *itobs(int n, char *ps);

int main(void)
{
	/* 创建Views联合, 并舒适化initialize struct box view */
	union Views box = { {true, YELLOW, true, GREEN, DASHED } };
	char bin_str[8 * sizeof(unsigned int) + 1];

	printf("Original box settings:\n");
	show_settings(&box.st_view);
	printf("\nBox settings using unsigned int view:\n");
	show_settings1(box.us_view);

	printf("bits are %s\n", itobs(box.us_view, bin_str));
	box.us_view &=  ~FILL_MASK;						/* 把表示填充色的位清0 */
	box.us_view |= (FILL_BLUE | FILL_GREEN);				/* 重置填充色 */
	box.us_view ^= OPAQUE;							/* 切换是否透明的位 */
	box.us_view |= BORDER_RED;						/* 错误的方法 */
	box.us_view &= ~STYLE_MASK;						/* 把样式的位清0 */
	box.us_view |= B_DOTTED;						/* 把样式设置为点 */
	printf("\nModified box settings:\n");
	show_settings(&box.st_view);
	printf("\nBox settings using unsighed int view:\n");
	show_settings1(box.us_view);
	printf("bits are %s\n", itobs(box.us_view, bin_str));

	return 0;
}

void show_settings(const struct box_props *pb)
{
	printf("Box is %s.\n", pb->opaque == true ? "opaque" : "transparent");
	printf("The fill color is %s.\n", colors[pb->fill_color]);
	printf("Border %s.\n", pb->show_border == true ? "shown" : "not shown");
	printf("The border color is %s.\n", colors[pb->border_color]);
	printf("The border style is ");
	switch(pb->border_style)
	{
		case SOLID:
			printf("solid.\n");
		break;
		case DOTTED:
			printf("dotted.\n");
		break;
		case DASHED:
			printf("dashed.\n");
		break;
		default:
			printf("unknown type.\n");
		break;
	}
}

void show_settings1(unsigned short us)
{
	printf("box is %s.\n", (us & OPAQUE) == OPAQUE ? "opaque" : "transparent");
	printf("The fill color is %s.\n", colors[(us >> 1) & 07]);
	printf("Border %s.\n", (us & BORDER) == BORDER ? "shown" : "not shown");
	printf("The border style is ");
	switch(us & STYLE_MASK)
	{
		case B_SOLID:
			printf("solid.\n");
		break;
		case B_DOTTED:
			printf("dotted.\n");
		break;
		case B_DASHED:
			printf("dashed.\n");
		break;
		default:
			printf("unknown type.\n");
		break;
	}
	printf("The border color is %s.\n", colors[(us >> 9) & 07]);
}

char *itobs(int n, char *ps)
{
	const static int size = CHAR_BIT * sizeof(int);

	for(int i = size - 1; i >= 0; i--, n >>= 1)
	{
		ps[i] = (01 & n) + '0';
	}
	ps[size] = '\0';

	return ps;
}

